Pneumatic sifter.



F. HOLL.

PNEUMATIC SIFTER. mmcwm man MAY 22. m4,

Patented Nov. 2, 1915.

w J A FRANZ HOLL, or WORMS-ON-THE-RI-IINE, GERMA Y.

PNEUMATIC SIFTER.

Application filed May 22 1914. Serial No. 840,356.

To all whom it may concern:

Be it known that I, FRANZ HoLL, engineer, a subjectof the German Emperor, and resident of Luisenstrasse the-Rhine, Germany, have invented new and useful Improvements in and Relating to Pneumatic Sifters, of which the following is a specification,

The present invention relates to an improved pneumatic sifter and has more special reference to that type in which undulatory motion is imparted to a definite quantity of air inclosed in blasts or waves of wind.

According to the present invention a ver tical structure is used in which a fan ro- 7 Such variation in the strength of the air current in successive horizontal layers is.

obtained, according to the present invention, by subjecting the stock while falling to the action of a vertical conical fan, or of a cylindrical fan used in combination with a conical casing. In the first case the air pressure is naturally strongest where the fan vanes are longest decreasing gradually with their lengthwhile, in the second case,

the same effect is produced by the increasing interval between fan and casing. Both.

typesof construction, can, if desired be combined byusing a conical fan m a comcal casing.

The casing may beconstituted by the sides of the cover of the machine, by a sieve, or by louver-like rings partly mserted one.

' in another or finally by a combination of the above.

Onelnethod of carrying out the invention is shown in the accompanying drawings in which Figure 1 is a part vertical section of the machine. Fig. 2 is a horizontal section on line A-B of Fig. 1.

In a cover 1 of any suitable form a vertical shaft 3, carrying a fan 4, is rotatably ournaled. The fan is tapered downward Specification of Letters Patent.

7, WVorms-on- I of small ,weaker rings 5 are disposed one above another the machine. The stock is thus subjected to the action of be omitted.

Patented Nova2, 1915.

and, in the present instance, comprisestwo,

larger and a. plurality of smaller, vanes. The latter serve the purpose ofsepa ting the air which flows" in behind the larger vanes and transforming it into a plurality vanes.

around the fan, forming a 'louver-li'kecas ing, likewise tapered downward and com: posed of four segment like parts. This'seg mental casing is surrounded by a gauze cove ering 6 also consisting of four parts. The feed-hopper 8 forthe stock is disposed around the shaft 3 on the head 7 above the fan. A screwed sleeve 9 engages movably over the lower cylindrical part of the hop:

Funnel-shaped per which'is also screwed so that the opening between the hopper and the upper fan casing 10, which acts as a spreader, may be increased or decreased as desired.

Openings 12 for the discharge of the coarse and openings 13 for the fine sifted products are provided in the bottom 11 of the cover. 1 Q 1 1 is a T ring, secured to the cover bottom 11, which by-engaging in a concentric groove in the bottom fan casing forms an air-tight joint, betweenthe two.

The operation of the device as fo1-' ,lowsz-The stock is poured into the feed hopper 8 and passes through the adjustable slit on to the spreader 10 whence it falls and is flung against the louver-like casing 5. A

continuous separation of the finer from the coarser parts takes place on the surface of these rings, the finer parts being carried up. ward through the openings between con secutive rings whereas the coarser parts accumulate thereon-falling off at "interiyals on to the surface of the ring immediately underneath tobe shifted anew and"'so on until they ,are collected through the'fopen he fineparticles, carried by the'air pressure upward-through the spaces separating the rings impinge on the, gauze screen 6,. where a further separation of the parts takes place, only the finest particles passing through the gauze to fall behind it and be removed through the opening 13.

For sifting materials not requiredto present a very high degree of fineness or uniformity, the casing 5 alone is sufficient, and

the gauze screen may in this case therefore By removing the casing 5 the gauze alone a in may be used for sifting in which case the stock rolls down its inclined surfaceand is blown through horizontally.

It is clear that the essence of the invention resides in the fact that the current of air and namely always of the same air, is driven through the fan in the form of distinct consecutive blasts, in such manner that the strength of the current varies continuously from one horizontal position to another. If

the fan tapers conically from top to bottom,"

a'continuous decrease of the maximum blast follows from the consideration that a fan .of lesser diameter produces a weaker blastthan a fan of greater diameter. The same "efi'ect is'obtained with a cylindrical tan in which case the shape of the casing must vary continuously, as though of constant strength at all heights the action of the blast on the stock will then vary continuously because the interval between fan and casing and consequently stock is continuously varied.

. The action of the baffie rings consists in transforming the air-waves enerated by the fan vanes intoa. plurality of more or plurality of sieves orof the louver acting rings, or a plurality of. combinations of the same may be arranged concentrically to each 1 other so asto sort the stock into a number of grades of fineness at one operation.

such case a correspondingly increased numher of delivery openings must be provided in the bottom;

;Having now particularly described and ascertained the nature of my said invention,

and in whatmanner the same is to beperformed, I declare that what I claim is 1. In a device of the character described, the combination of a fan including vanes of varying radius, a separating casing surrounding said fan, and means for feeding material through. said casing, substantially as described.

2. Ina device of the character descrlbed,

the combination of blast creating means, a separating casing surrounding said means and comprising a series of frusto-conical rings assembled in overlapping relation, and means for feeding material to said casing,

substantially as described.

3. In a device of the character described, 7

spreader arranged beneath said introducing means for directing the material between. said casing and blast producing means, and a movable sleeve associated with said intro ducing means and adapted to be adjusted above said conical spreader to regulate the quantity of material introduced, substantially as described.

5.. In a device of the character described, the combination of a housing, a shaft journaled in said housing, a fan mounted on said shaft and including tapering vanes of varying radius, a separating casing sur rounding said fan and comprising a series of frusto-conical rings assembled in louverformation and tapering toward the base of said casing, and a mesh embracing. said rings, a hopper forintroducing material to said casing, a conical spreader rotatable with said fan and arranged beneath said hopper, and a movable sleeve on said hopper for adjustment above said spreader for regulating the quantity of material introduced', substantially as described.

Mannheim, Germany, dated this'lQth day of'May A. D. 1914.

In testimony, that I claim the foregoing as my invention, I have signed my name in presence of two witnesses, this twelfth day FRANZ nonn of May A. D. 1914.

'Witnesses ANNA CRUsIz, Josnrn Hansen. 

